This invention relates to a method of and an apparatus for producing an iron core.
An iron core for a motor is formed from a strip by blanking. This iron core is usually blanked as a substantially linear iron core.
This linear iron core comprises a plurality of magnetic pole pieces which are interconnected into a linear configuration by interconnecting portions, each magnetic pole piece comprising a yoke portion, and a tooth portion.
A plurality of such iron cores are stacked and laminated together, and thereafter windings are wound around the stacks of tooth portions, respectively, and the interconnecting portions are bent so as to form the laminated iron core assembly into an annular shape, thereby producing a core (stator) of a motor (see, for example, JP-A-11-156455).
For producing the above substantially-linear iron core, there is conventionally used an iron core-producing apparatus which comprises guide means for guiding the strip linearly in one direction, a punch for blanking an iron core from the strip, and a die located beneath the punch.
In such a conventional producing apparatus, when the strip is guided onto the die by the guide means, the punch is driven into the die, thereby blanking an iron core from the strip.
In this conventional producing apparatus, the punch and the die are disposed such that their longitudinal direction is parallel to the direction of the width of the strip. Therefore, in the blanking step, the iron core is blanked from the strip in such a manner that the longitudinal direction of the iron core is disposed parallel to the direction of the width of the strip (see, for example, JP-A-11-156455).
In the production of the conventional iron core, the iron core is blanked, with its longitudinal direction disposed parallel to the direction of the width of the strip, and therefore in order to increase the overall length of the iron core, it has been necessary to increase the width of the strip.
And besides, in the conventional iron core-producing apparatus, the punch and the die are disposed in such a manner that their longitudinal direction is parallel to the direction of the width of the strip as described above. Therefore, when the width of the strip is increased in order to increase the overall length of the iron core, a strip conveyance width of the guide means must be increased in accordance with the increased width of the strip; otherwise, the iron core cannot be conveyed, and therefore can not be produced. In addition, unless a longitudinal width of a blanking drop hole, formed in the die, is increased according to the width of the strip, the iron core can not be produced from the strip by blanking.
In order to thus increase the overall length of the iron core, there have been encountered problems that the width of the strip must be increased and that the whole of the iron core-producing apparatus becomes large in size.
When the whole of the iron core-producing apparatus becomes large in size, it is required to use a pressing device of a large size, which has been very disadvantageous.